Quite to the contrary...

"...Vasuupalis!" Mary exclaims the rest of the chant.

"Vasuupalis." Penelope says confidently at exactly the same moment.

Mary's hex beams out of her hand like brilliant pulse of light, and shoots through the air at her silly older sister.

...And then, the beam of light bounces off of Penelope like she's a mirror, and rebounds directly into Mary herself.

"HUH?!" Mary squeaks as her own hex hits her, settling its cruel curse down into her own body and mind. "NO!"

As Mary collapses to the ground, all her clothing disappearing, and some kind of small beige seal appearing over her vulva, her sister calmly inspects her own fingers, blowing a little bit of dust off of the tips.

And as Mary ends up on her back, with her hands clasped to her buttocks, unable to remove them, Penelope calmly asks her sister a question.

"Have you even heard of counter magic, my dear sister? You get taught it in your 4th year of senior training. So, if you hadn't been exiled, you'd be learning it this year. Essentially, you can turn any offensive spell right back on its caster. All you have to do is know that you are going to be the target, and know which family of magic the spell will be from, so that you can say the subdeclaration at the same moment. And I'm afraid, dear sister, that it was painfully predictable that you would cast a transformation hex, considering that this is what you've been doing up and down the country for the last several weeks."

"No! Fuck!" Mary snarls. She still can't believe that this is happening to her.

"Now, let's see, what exactly is this hex? Anhara... Levilis!"

Penelope's identification magic allows her to inspect the details of the hex that Mary is now succumbing to.

"A permanent hex? Wow sister, you're right, you really are powerful, if you are able to cast permanent hexes! Now, let's see... It triggers every time you cast a spell... And prevents you from casting any more spells by disintegrating your clothing, and forcing you to press your palms up against your buttocks. Very cruel! And let's see... Your hands will only be unsealed when something long and hard, is inserted deep inside your butthole. How degrading! But wait, there's a bit more... A permanent magical vaginal seal, to prevent the victim from ever enjoying the pleasure of vaginal or clitoral stimulation ever again. Unbelievable! Mary, you truly are evil."

Somehow, hearing the details of her new permanent predicament from her sister's mouth makes the reality of it that much more difficult for Mary to bear. She stares at her older sister with a dark, hateful gaze. But since she can't remove her hands from her buttocks, she can't cast any more offensive spells, and so is close to helpless.

"I can't wait until the others back home see this. You're going to be the laughing stock of the island, Mary! How hilariously pathetic!" Penelope turns her back on Mary, and facing the entrance to the cave, begins to summon a Portal Gate, a teleportation window that will allow her to take Mary back to Illustris with her. "The good news is that your exile can now be cancelled. The great news is that you'll spend the rest of your life stuck like that, harmless, humbled, and humiliated."

Mary snarls. "I'll have my **** sister, mark my words."

Penelope laughs, not even bothering to turn around. "How? Unless someone sticks something up your asshole, you're stuck like that, completely impotent and powerless. Do you think we're going to free your hands when we get back? No way. You're going to be stuck like that for life, spoon-fed your food, and probably displayed in public as a warning to-"

While Penelope rants, Mary draws upon the last bit of magic she still has access to - the wooden spoon that is still obediently stirring the stew. Thanks to the fat cushion of her buttcheeks, she can move her fingers just enough to send a new command to that spoon which is already under her magic control, without having to cast a brand new spell. It silently rises out of the stew, and then zips handle-first towards Mary's spread-wide pucker.

By the time Penelope has detected what's going on behind her, it's too late to stop it. The wooden spoon pushes inside Mary's asshole, and as soon as it gets deep enough, her hands are freed.

"Haciensha...!" Penelope swirls and urgently tries to begin casting a new offensive spell, but it's much too late. Mary mastered self-teleportation a long time ago, so as soon as her hands are free, it's only a split second before she has vanished from the spot, disappearing from the cave, and reappearing somewhere else entirely, perhaps countless miles from here.

"Fuck!" Penelope snarls, as she watches the wooden spoon clatter to the ground where Mary's naked body had just been.

Mary appears in the first place she thought of in that moment, which was, for some reason, a dark corner of the general store of the shopkeeper whose daughter she turned into a sex doll. Perhaps it's because that's the moment where this arc of her life all began, that this is the place that came to mind. But of course, as she's just cast another spell, her hands immediately become glued to her buttocks again, and this time she has no existing control over a narrow wooden utensil with which to free herself.

Everything about what just happened is extremely shit, but she doesn't have time to reflect on what the long term future has in store for her right now.

What happens in the short term is much more important, and depends on who exactly finds her lying here, naked and ****, and what they decide to do with her...